The development and manufacture of hearing aids generally utilises an average ear response for optimizing the functionality of the hearing aid. However, investigations, such as described in “Earphone pressure response in ear couplers”, Technical Report TR-7 presented at the 83rd meeting of the Acoustical Society of America, 21 Apr. 1972, by R. M. Sachs and M. D. Buckhard, have shown big individual deviations from the average, which consequently will affect the adaptation of the hearing aid to the user.
The Audio Engineering Society's “Convention Paper 5753” presented at the 114th convention 22-25 Mar. 2003 Amsterdam, Netherlands, by Carl Hetherington and Anthony I. Tew describe how the pinna shape may be parameterized for the estimation of head-related acoustic transfer functions. This article discloses means for scanning a pinna shape (by CT scanning or by camera) and means for calculating sound pressure response of at an eardrum.
Further, in Journal of the Acoustical Society of America November 2002, volume 112, issue 5, the article “Measurement and numerical simulation of the changes in the open-loop transfer function in hearing aid as a function telephone handset proximity” by Gilles A. Daigle and Michael R. Stinson explains the use of boundary element method (BEM) for determining the open loop transfer function in hearing aids and how, for example, a telephone handset affects the open loop transfer function.
Neither of these presentations, however, provides means for adapting a hearing aid in accordance with a user's individual physical ear-shape or individual acoustic response of said ear-shape.